I think this is quite common. Either money laundering or a legitimate front for something else. There was a very good Bosnian restaurant in my town about 15 to 20 years ago, but there was only one waiter, who may also have been the cook, and one half of the restaurant was always slightly darker and always had people who clearly "belonged there" sitting at a table in the corner. Perhaps I'm being unfair and it was just a gathering place for the local community and they decided to make a little money off of it as long as they had it, but it always gave me a weird vibe. In a different town I lived in there was an African restaurant that was never open, but always had two or three people in it drinking coffee. It was there for years and I never once saw it open or empty.